1. Field of the Invention
The present invention relates to collecting data using wired sensors connected to wireless nodes. More particularly, the invention relates to systems and methods for collecting data from wired sensors communicating with a wireless node via a data bus, the wireless node wirelessly communicating with a central data collection device.
2. Background
Much wireless sensor network research focuses on automated node location, particularly for three-dimensional mapping of environmental conditions in situations where it is impractical for users to manually enter fixed node locations, or where the nodes move through the environment over time. However, the environments to be monitored often include freshwater, seawater, or moist soil—conductive media in which radio waves are severely attenuated.
Wired sensor networks using permanently connected sensors at fixed locations do not have the attenuation problems associated with wireless sensor networks. Further, wired sensor networks enable data mapping. However, such wired sensor networks do not provide for movement of the sensors through the environment or allow easily changing the order of sensors in the network. With respect to changing the order of sensors in a wired network, current methods for automatically determining sensor sequence require addition of two or more extra wire connections. For example, “Chain Mode” thermometer chips have an additional pair of pins that provide an input and output for each chip to be connected in series, enabling sequence detection with five wires. Another method allows seven pins on the chip to be either floated or grounded, and the resulting configuration reported on a data line. With these chips, it would be possible to make 128 unique connectors which would provide a telltale physical address for sensors depending on their location along the network. Ten wires would be needed to take full advantage of this method for sequence detection. However, installing connectors for individual wires is a time-consuming process when assembling new hardware. Further, in humid environments, such as a waterborne environmental sensor network, each additional make-or-break connection increases the risk of failure due to contact corrosion.
Still further, wireless and wired sensor networks generally require manually programming of calibration coefficients, methods of operation and similar information for newly developed sensors, which makes adding newly developed sensors to existing networks problematic.